Hair loss may occur due to a variety of conditions and may affect anyone: men, women and children. Hair loss conditions include, but are not limited to, alopecia capitis totalis, i.e., loss of all scalp hair, alopecia universalis, i.e., loss of hair over the whole body, alopecia greata, i.e., patchy hair loss, and androgenetic alopecia, i.e., male pattern baldness. Medications are available to treat alopecia including minoxidil, finasteride, corticosteroids and anthralin. However, any new hair growth resulting from the medication generally stops upon discontinuation of the medication.
More aggressive hair restoration methods include hair transplants and scalp reduction surgery. Hair transplantation entails excision of a full-thickness strip of scalp tissue from the back of the head, dissecting the excised scalp tissue into hundreds of “follicular unit grafts”, each containing from one to several hairs, and implanting the grafts into recipient sites created by making stab wounds in the bald sections of the scalp. Hair transplantation creates no new hair follicles and often not all of the explanted follicles successfully transplant. Scalp reduction surgery, which is becoming less popular, aims to surgically reduce the area of bald skin on subject's head. Both hair transplantation and scalp reduction surgery are expensive and may be painful. Moreover, both carry possible risks of infection and scarring.
It is well known that specific cells within the hair follicle, including epidermal stem cells and dermal papilla cells, have the capacity to induce follicle neogenesis. Attempts have been made to exploit the inductive capabilities of these cells, including injecting dermal papilla cells directly into the skin and implanting plucked hairs carrying epithelial cells having various proliferative and differentiative characteristics. Previous attempts at producing follicle neogenesis have failed to produce reliable, reproducible and cosmetically satisfactory results.